The breakfast hype

One of the changes she made: Making sure that she ate a good breakfast.

Mark Mattson, a neuroscientist at the National Institute on Aging, disdains the morning repast. He hasn't eaten breakfast in 20 years, ever since he started running early in the mornings.

He says he's skinny and healthy and never felt better.

Whatever you do, don't skip breakfast.

Breakfast: It's the most important meal of the day.

Such pronouncements carry almost the aura of nutritional religion: carved in stone, not to be questioned. But a few nutritionists and scientists are questioning this conventional wisdom.

They're not challenging the practice of sending children off to school with some oat bran or eggs in their belly. They acknowledge the many studies reporting that children who eat breakfast get more of the nutrients they need and pay more attention in class.

They do say, however, that the case for breakfast's benefits is far from airtight -- especially for adults, many of whom, if anything, could stand skipping a meal.

"For adults, I think the evidence is mixed," says Marion Nestle, professor of nutrition, food studies and public health at New York University who hasn't eaten breakfast in years because she is just not hungry in the morning.

"I am well aware that everyone says breakfast is the most important meal of the day, but I am not convinced," Nestle wrote in her book, "What to Eat." (She later received many e-mails from readers telling her that they were relieved to hear it.) "What you eat -- and how much -- matters more to your health than when you eat."

A few scientists go further than this. They say it may be more healthful for adults to skip breakfast, as long as they eat carefully the rest of the day.

"No clear evidence shows that the skipping of breakfast or lunch (or both) is unhealthy, and animal data suggest quite the opposite," wrote Mattson, possibly the ultimate anti-breakfast iconoclast, last year in the medical journal the Lancet. Advice to eat smaller and more frequent meals, he wrote, "is given despite the lack of clear scientific evidence to justify it."

Mattson admits that he hasn't proven his case yet. His studies are still preliminary.